I think she (sister) liked Kazoumi romantically so of course she'd want to know for sure if they're actually related. As for Kazoumi's goal he wanted uke for himself but his ways were not very great, for some reason he's gone psycho lol and the Mistress when she was having an affair with the dad sha did it with some guy so its not that she was lying she wasn't sure who Kazoumi's father either.
btw please don't ask why i understand because i myself doesn't know why i wasted my time reading this crap like ughhh recommend me something good pleaseeee ;-;
I m sure with the fact that the mistress didn't know because kazuomi knew since the chapter he wasn't related by blood so I don't share that idea...about a good one try this one Tonari no Usotsuki ...very good and more realistic
1. Cuz she a hoe
2. He got brain damaged when he fell
3. Moneeyy
Heyy I really don't understand...why the sister attitude change? Why was the real goal of the blackhaired because it wasn't exactly revenge for what i saw... Why the mistress make up this lie...I m completely lost